﻿namespace ViewModel
{
    using System;
    using System.Diagnostics;
    using System.Windows.Input;

    /// <summary>
    /// Class for creating commands for viewmodels
    /// </summary>
    public class RelayCommand : ICommand
    {
        #region Constructors

        public RelayCommand(Action<object> execute)
            : this(execute, null)
        {
        }

        public RelayCommand(Action<object> execute, Predicate<object> canExecute)
        {
            if (execute == null)
            {
                throw new ArgumentNullException("execute");
            }

            _execute = execute;
            _canExecute = canExecute;
        }

        #endregion

        #region ICommand Members

        [DebuggerStepThrough]
        public bool CanExecute(object parameter)
        {
            return _canExecute == null ? true : _canExecute(parameter);
        }

        public event EventHandler CanExecuteChanged
        {
            add
            {
                if (_canExecute != null)
                {
                    CommandManager.RequerySuggested += value;
                }
            }

            remove
            {
                if (_canExecute != null)
                {
                    CommandManager.RequerySuggested -= value;
                }
            }
        }

        public void Execute(object parameter)
        {
            _execute(parameter);
        }

        #endregion

        #region Fields

        private readonly Action<object> _execute;

        private readonly Predicate<object> _canExecute;

        #endregion
    }
}
